1. Field of the Invention
The present invention relates to a projection-type display apparatus that employs a liquid-crystal shutter system for three-dimensional image viewing.
2. Description of the Related Art
In a conventional projection-type display apparatus such as one disclosed in Japanese Patent Application Laid-open No. 2006-91867, an incoherent and relatively low luminescence light source, such as a mercury lamp or a light-emitting diode (LED), is used. On the other hand, a laser beam is superior in terms of directivity and luminescence, and therefore a laser is preferable as a light source for the projection-type display apparatus. A projection-type display apparatus has been developed that includes a laser light source as an ideal point light source with excellent focusing property and an optical engine that is made suitable for a low-profile design of the projection-type display apparatus by making an optical system compact, which is disclosed, for example, in Japanese Patent Application Laid-open No. 2000-131665.
Using a light source that is superior in focusing property, such as a laser light source, enables the optical system to be made compact, thereby facilitating a low-profile design of the projection-type display apparatus. However, a space is required in the apparatus for arranging components such as a laser light source, a power supply circuit, and a signal processing circuit, which interferes with a low-profile design of the apparatus.
In recent years, a demand for viewing three-dimensional images with a large projection-type display apparatus, particularly, a commercial television product, has been increasing. Among various methods proposed for providing viewing three-dimensional images, the easiest and most inexpensive method is to use liquid-crystal shutter glasses. However, in the projection-type display apparatus using a laser light source, annular color unevenness may appear on a screen when viewed through the liquid-crystal shutter glasses due to strong polarization properties of the laser light source, thus degrading image quality.